Process of obtaining pure tungstic acid.



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UNITED STATES PATENT caries.

TOKUSEI BAN, 0F TOKYO, JAPAN.

PROCESS OF OBTAINING PURE TUNGSTIC ACID.

Specification of Letters Patent. Patented Dec. 31, 1912, Application filed January 24, 1912. Serial ITO/673,168.

To uZZ whom it may concern.

Be it known that I, TOKUSEI BAN, a subject of the Emperor of Japan, residing at No. 12 TlakagLCho, Aoyama, Akasaka-Ku, city of Tokyo, Empire of Japan, have invented new and useful Improvements in l rocesses ot' Obtaining Pure Tungstic Acid, of which the following is a specification.

This invention relates to processes for obtaining pure tungstic acid, and hasfor its object to and cheapen such proc- To the liquor a small quantity of citric acid is then added, together with a sufficient quantity of water, and the solution is let stand for about two hours. l-ilthough the ferric chlorid thus dilutedwillbe more or less decomposed so as to produce an insoluble chlorid of bibasic iron, still the citric acid present, will convert it into a soluble citrate of iron. The clear liquor thus produced will be poured out and the residuewashed thoroughly with clean water. This will produce pure tungstic acid containing even 'not a trace of iron. I have found however that in cases where theore to be operated upon contains simplify css particularly by avoiding the necessity of using aqua regia, the use of which agent unavoidably rciu'lers the operation troublesome. from the generationof an injurious ga in previously used methods.

To this end the invention consists in first treating the wol'l'ramite with strong hydrochloric acid. heating gently, then after removing the greater part of the dissolved iron, and other impurities, treating the resulting tungstic acid with a concentrated solution of bleaching powder, gradually adding thereto a suitable quantity of hydrosary, after passing through the aforesaid in ammonia. Then after filtration, the solution will be evaporated to a dry state. Ammonium t-ungstate thus obtained will be then heated to a red heat thereby causing the ammonia to volatilize and leaving pure tungstic acid.

chloric acid, stirring, and further adding Hcrctofore, the aqua regia has been a small quantity of citric acid, together mostly used in such treatment. This prowith a sullicient quantity of fresh water, duces not only in uriOus gas during the op after which the insoluble substances jected to a further washing with distilled water. In cases where theorc contains any insoluble matters, such as silica and clay, etc. the ore after being treated in the aforesaid manner, will be dissolved in ammonia and by subsequently filtering, evaporating and heating. to a red heat pure tungstic acid is produced.

First introduce finely powdered wolfra mite. FclVO into strong hydrochloric acid and heat it gently in usual manner. lVhen the greater part of the iron, as well as other substances contained in the ore are dissolved, the solution is then allowed to cool. Then pour away the clear solution and thoroughly wash the residue with clean water. The residue thus treated will be nextplaced in the concentrated solu; tion of bleaching powder, and a suitable quantity of hydrochloric acid is added and stirred up slowly. It will be observed that by this agitation the calcium hypochlorite containedin the bleaching powder, acted uponbythe hydrochloric acid, will liberate arc suboration, but has the disadvantage of precipitating insoluble iron salts, which defects are obviated by my present invention.

claim:

The process of obtaining pure tungstic acid, which consists in first introducing into a strong hydrochloric acid a finely pow dered wolframite and heating gently until ,the greater portion of, the soluble substances are dissolved, in cooling the solution and after pouring away the clear solution, washing the residue in the usual manner, subscquently treating with concentrated solu tion of bleaching powder, gradually adding thereto a suitable quantity of hydrochloric in further addacid with constant stirring.

ing a small quantity of citric acid together with suflicient water and after pouring away the clear liquor thoroughly washing the residue with fresh water and drying, substantially as set forth. 7

In testimony whereof I affix my signature presence of two witnesses.

TOKUSEI BAN.

chlorin in a nascent state, which, acting Witnesses:

upon iron, and other substances, still eXist- GENJI KURIBARA,

ing in the residue, will make them soluble. Tooo OKUBO.

Copies of this patent may be obtained for five cents each, h addressing the Commissioner of Patents,

Washington, D. 0.

any insoluble .substances,- such as silica, clay, etc .,'1t'1s further necestreatment, to dissolve the insoluble'rcsidue 

